The present invention, in some embodiments thereof, relates to an apparatus and a satellite antenna and, more particularly, but not exclusively, to an apparatus and a method for vehicle-mounted antennas for satellite communication.
There is increasing interest in implementing broadband communication systems on various forms of mobile platforms, for example, maritime vessels and land vehicles. With a broadband satellite communication system that has an antenna mounted on a vehicle, the antenna is used to help form a communications link with a space-based satellite in geosynchronous orbit. The antenna forms part of a communications terminal that is carried by the vehicle.
Antennas with an ability to track, with high precision, communication satellites from mobile platforms such as aircraft, ships and land vehicles are required, inter alia, for optimizing data rate, improving the efficiency of downlink and uplink transmission, and/or preventing interference with satellites orbiting adjacent to a target satellite. Such antennas allow mobile satellite communication platforms that have relatively high attitude accelerations, such as aircraft and land vehicles to receive signals from and/or to transmit signals to satellites such as geostationary satellites.
In order to collect the signals from the remote sources and/or in order to transmit signals to thereto, it is necessary to keep the antenna pointed at the satellite while taking the movement of a vehicle into account. In order to allow the antenna to point at the satellite, the vehicle-mounted antennas are made to track side-to-side (azimuth) and up and down (elevation). However, it should be noted that in order to avoid interfering with the smooth airflow over the vehicle or adversely affecting the aesthetics of the vehicle, the profile of the vehicle-mounted antennas has to remain low.
For example, International Patent Application Pub. No. WO2008/114246, published on Sep. 25, 2008 describes an antenna for communicating with a satellite from a moving vehicle. The antenna comprises a transmitter for generating a transmission signal, main and sub reflectors, and a waveguide associated with the transmitter for conducting the transmission signal toward the sub reflector. The sub reflector is configured for redirecting the transmission signal toward the main reflector; the main reflector is configured for projecting the redirected transmission signal as an antenna beam toward the satellite.